Ion assisted deposition for rare-earth oxide based thin film coatings on process rings

ABSTRACT

A ring shaped body includes a top flat region, a ring inner side and a ring outer side. The ring inner side comprises an approximately vertical wall. A conformal protective layer is disposed on at least the top flat region, the ring inner side and the ring outer side of the ring shaped body. The protective layer has a first thickness of less than 300 μm on the top flat region and a second thickness on the vertical wall of the ring inner side, where the second thickness is 45-70% of the first thickness.

RELATED APPLICATIONS

This patent application is a divisional application of U.S. patentapplication Ser. No. 14/032,098, filed Sep. 19, 2013, which claims thebenefit under 35 U.S.C. §119(e) of U.S. Provisional Application No.61/856,597, filed Jul. 19, 2013. Patent application Ser. No. 14/032,098is incorporated by reference herein.

TECHNICAL FIELD

Embodiments of the present invention relate, in general, to chamberprocess rings having a thin film plasma resistant protective layer.

BACKGROUND

In the semiconductor industry, devices are fabricated by a number ofmanufacturing processes producing structures of an ever-decreasing size.Some manufacturing processes such as plasma etch and plasma cleanprocesses expose a substrate to a high-speed stream of plasma to etch orclean the substrate. The plasma may be highly corrosive, and may corrodeprocessing chambers and other surfaces that are exposed to the plasma.

Currently process kit rings have performance issues because of higherosion rate and plasma chemistry interaction. Typically an insert ringand single ring are made out of quartz for conductor etch and Si fordielectric etch. These rings sit around the wafer to make the plasmadensity uniform for uniform etching. However, quartz and Si have veryhigh erosion rates under various etch chemistries and bias powers.Severe erosion of the rings can result in on wafer based particledefects, process shift, deposition of erosion bi-product on otherchamber components and reduction in chamber yield.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that differentreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

FIG. 1 depicts a sectional view of one embodiment of a processingchamber.

FIG. 2A depicts a deposition mechanism applicable to a variety ofdeposition techniques utilizing energetic particles such as ion assisteddeposition (IAD).

FIG. 2B depicts a schematic of an IAD deposition apparatus.

FIGS. 3-4 illustrate cross sectional side views of articles (e.g.,process kit rings) covered by one or more thin film protective layers.

FIG. 5 illustrates a perspective view of a process ring having a rareearth oxide plasma resistant layer, in accordance with one embodiment.

FIG. 6 illustrates one embodiment of a process for forming one or moreprotective layers over a ring.

FIG. 7 shows erosion rates of various materials exposed to dielectricetch CF₄ chemistry, including erosion rates of multiple different IADcoatings generated in accordance with embodiments described herein.

FIGS. 8-9 illustrate erosion rates for thin film protective layersformed in accordance with embodiments of the present invention.

FIGS. 10-11 illustrate roughness profiles for thin film protectivelayers formed in accordance with embodiments of the present invention.

FIG. 12 shows erosion rates of various materials exposed to a CF₄—CHF₃trench chemistry at low bias.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention provide an article such as a ringthat has an erosion resistant thin film protective layer to enhance alifetime of the ring and reduce on-wafer defects without affectingplasma uniformity. The protective layer may have a thickness up toapproximately 300 μm, and may provide plasma corrosion resistance forprotection of the ring. The protective layer may be formed on the ringusing ion assisted deposition (IAD) (e.g., using electron beam IAD(EB-IAD)). The thin film protective layer may be Y₃Al₅O₁₂ (YAG), Y₄Al₂O₉(YAM), Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂ (EAG), Gd₃Al₅O₁₂ (GAG), a ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂, oranother rare-earth oxide. The improved erosion resistance provided bythe thin film protective layer may improve the service life of the ring,while reducing maintenance and manufacturing cost. Additionally, the IADcoating can be applied thick enough to provide a longer life time forthe ring. IAD coatings can be applied and later refurbished at low cost.

FIG. 1 is a sectional view of a semiconductor processing chamber 100having one or more chamber components that are coated with a thin filmprotective layer in accordance with embodiments of the presentinvention. The processing chamber 100 may be used for processes in whicha corrosive plasma environment is provided. For example, the processingchamber 100 may be a chamber for a plasma etch reactor (also known as aplasma etcher), a plasma cleaner, and so forth. Examples of chambercomponents that may include a thin film protective layer include asubstrate support assembly 148, an electrostatic chuck (ESC) 150, a ring(e.g., a process kit ring or single ring), a chamber wall, a base, a gasdistribution plate, a showerhead, a liner, a liner kit, a shield, aplasma screen, a flow equalizer, a cooling base, a chamber viewport, achamber lid 104, a nozzle, and so on. In one particular embodiment, aprotective layer 147 is applied over a ring 146.

The thin film protective layer 147, which is described in greater detailbelow, is a rare earth oxide layer deposited by ion assisted deposition(IAD). The thin film protective layer 147 may include Y₂O₃ and Y₂O₃based ceramics, Y₃Al₅O₁₂ (YAG), Y₄Al₂O₉ (YAM), Er₂O₃ and Er₂O₃ basedceramics, Gd₂O₃ and Gd₂O₃ based ceramics, Er₃Al₅O₁₂ (EAG), Gd₃Al₅O₁₂(GAG), Nd₂O₃ and Nd₂O₃ based ceramics, YAlO₃ (YAP), Er₄Al₂O₉ (EAM),ErAlO₃ (EAP), Gd₄Al₂O₉ (GdAM), GdAlO₃ (GdAP), Nd₃Al₅O₁₂ (NdAG), Nd₄Al₂O₉(NdAM), NdAlO₃ (NdAP), and/or a ceramic compound comprising Y₄Al₂O₉ anda solid-solution of Y₂O₃—ZrO₂. The thin film protective layer may alsoinclude YF₃, Er—Y compositions (e.g., Er 80 wt % and Y 20 wt %), Er—Al—Ycompositions (e.g., Er 70 wt %, Al 10 wt %, and Y 20 wt %), Er—Y—Zrcompositions (e.g., Er 70 wt %, Y 20 wt % and Zr-10 wt %), or Er—Alcompositions (e.g., Er 80 wr % and Al 20 wt %).

The thin film protective layer 147 may also be based on a solid solutionformed by any of the aforementioned ceramics. With reference to theceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂,in one embodiment, the ceramic compound includes 62.93 molar ratio (mol%) Y₂O₃, 23.23 mol % ZrO₂ and 13.94 mol % Al₂O₃. In another embodiment,the ceramic compound can include Y₂O₃ in a range of 50-75 mol %, ZrO₂ ina range of 10-30 mol % and Al₂O₃ in a range of 10-30 mol %. In anotherembodiment, the ceramic compound can include Y₂O₃ in a range of 40-100mol %, ZrO₂ in a range of 0-60 mol % and Al₂O₃ in a range of 0-10 mol %.In another embodiment, the ceramic compound can include Y₂O₃ in a rangeof 40-60 mol %, ZrO₂ in a range of 30-50 mol % and Al₂O₃ in a range of10-20 mol %. In another embodiment, the ceramic compound can includeY₂O₃ in a range of 40-50 mol %, ZrO₂ in a range of 20-40 mol % and Al₂O₃in a range of 20-40 mol %. In another embodiment, the ceramic compoundcan include Y₂O₃ in a range of 70-90 mol %, ZrO₂ in a range of 0-20 mol% and Al₂O₃ in a range of 10-20 mol %. In another embodiment, theceramic compound can include Y₂O₃ in a range of 60-80 mol %, ZrO₂ in arange of 0-10 mol % and Al₂O₃ in a range of 20-40 mol %. In anotherembodiment, the ceramic compound can include Y₂O₃ in a range of 40-60mol %, ZrO₂ in a range of 0-20 mol % and Al₂O₃ in a range of 30-40 mol%. In other embodiments, other distributions may also be used for theceramic compound.

In one embodiment, an alternative ceramic compound that includes acombination of Y₂O₃, ZrO₂, Er₂O₃, Gd₂O₃ and SiO₂ is used for theprotective layer. In one embodiment, the alternative ceramic compoundcan include Y₂O₃ in a range of 40-45 mol %, ZrO₂ in a range of 0-10 mol%, Er2O3 in a range of 35-40 mol %, Gd₂O₃ in a range of 5-10 mol % andSiO₂ in a range of 5-15 mol %. In a first example, the alternativeceramic compound includes 40 mol % Y₂O₃, 5 mol % ZrO₂, 35 mol % Er₂O₃, 5mol % Gd₂O₃ and 15 mol % SiO₂. In a second example, the alternativeceramic compound includes 45 mol % Y₂O₃, 5 mol % ZrO₂, 35 mol % Er₂O₃,10 mol % Gd₂O₃ and 5 mol % SiO₂. In a third example, the alternativeceramic compound includes 40 mol % Y₂O₃, 5 mol % ZrO₂, 40 mol % Er₂O₃, 7mol % Gd₂O₃ and 8 mol % SiO₂. In one embodiment, the thin filmprotective layer 147 includes 70-75 mol % Y₂O₃ and 25-30 mol % ZrO₂. Ina further embodiment, the thin film protective layer 147 is a materialentitled YZ20 that includes 73.13 mol % Y₂O₃ and 26.87 mol % ZrO₂.

Any of the aforementioned thin film protective layers may include traceamounts of other materials such as ZrO₂, Al₂O₃, SiO₂, B₂O₃, Er₂O₃,Nd₂O₃, Nb₂O₅, CeO₂, Sm₂O₃, Yb₂O₃, or other oxides.

The thin film protective layer 147 may be an IAD coating applied overdifferent ceramics including oxide based ceramics, Nitride basedceramics and Carbide based ceramics. Examples of oxide based ceramicsinclude SiO₂ (quartz), Al₂O₃, Y₂O₃, and other metal oxides having thechemical formula M_(x)O_(y). Examples of Carbide based ceramics includeSiC, Si—SiC, and so on. Examples of Nitride based ceramics include AN,SiN, and so on. IAD coating target material can be calcined powders,preformed lumps (e.g., formed by green body pressing, hot pressing, andso on), a sintered body (e.g., having 50-100% density), or a machinedbody (e.g., can be ceramic, metal, or a metal alloy).

As illustrated, the ring 146 has a thin film protective layer 133, 134,in accordance with one embodiment. However, it should be understood thatany of the other chamber components, such as those listed above, mayalso include a thin film protective layer.

In one embodiment, the processing chamber 100 includes a chamber body102 and a lid 130 that enclose an interior volume 106. The lid 130 mayhave a hole in its center, and a nozzle 132 may be inserted into thehole. The chamber body 102 may be fabricated from aluminum, stainlesssteel or other suitable material. The chamber body 102 generallyincludes sidewalls 108 and a bottom 110.

An outer liner 116 may be disposed adjacent the sidewalls 108 to protectthe chamber body 102. The outer liner 116 may be fabricated and/orcoated with a thin film protective layer. In one embodiment, the outerliner 116 is fabricated from aluminum oxide.

An exhaust port 126 may be defined in the chamber body 102, and maycouple the interior volume 106 to a pump system 128. The pump system 128may include one or more pumps and throttle valves utilized to evacuateand regulate the pressure of the interior volume 106 of the processingchamber 100.

The lid 130 may be supported on the sidewall 108 of the chamber body102. The lid 130 may be opened to allow access to the interior volume106 of the processing chamber 100, and may provide a seal for theprocessing chamber 100 while closed. A gas panel 158 may be coupled tothe processing chamber 100 to provide process and/or cleaning gases tothe interior volume 106 through the nozzle 132. The lid 130 may be aceramic such as Al₂O₃, Y₂O₃, YAG, SiO₂, AN, SiN, SiC, Si—SiC, or aceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.The nozzle 132 may also be a ceramic, such as any of those ceramicsmentioned for the lid.

Examples of processing gases that may be used to process substrates inthe processing chamber 100 include halogen-containing gases, such asC₂F₆, SF₆, SiCl₄, HBr, NF₃, CF₄, CHF₃, CH₂F₃, F, NF₃, Cl₂, CCl₄, BCl₃and SiF₄, among others, and other gases such as O₂, or N₂O. Examples ofcarrier gases include N₂, He, Ar, and other gases inert to process gases(e.g., non-reactive gases). A substrate support assembly 148 is disposedin the interior volume 106 of the processing chamber 100 below the lid130. The substrate support assembly 148 holds the substrate 144 duringprocessing. A ring 146 (e.g., a single ring) may cover a portion of theelectrostatic chuck 150, and may protect the covered portion fromexposure to plasma during processing. The ring 146 may be silicon orquartz in one embodiment. The ring 146 includes the thin film protectivelayer 147.

An inner liner 118 may be coated on the periphery of the substratesupport assembly 148. The inner liner 118 may be a halogen-containinggas resist material such as those discussed with reference to the outerliner 116. In one embodiment, the inner liner 118 may be fabricated fromthe same materials of the outer liner 116. Additionally, the inner liner118 may be coated with a thin film protective layer.

In one embodiment, the substrate support assembly 148 includes amounting plate 162 supporting a pedestal 152, and an electrostatic chuck150. The electrostatic chuck 150 further includes a thermally conductivebase 164 and an electrostatic puck 166 bonded to the thermallyconductive base by a bond 138, which may be a silicone bond in oneembodiment. The mounting plate 162 is coupled to the bottom 110 of thechamber body 102 and includes passages for routing utilities (e.g.,fluids, power lines, sensor leads, etc.) to the thermally conductivebase 164 and the electrostatic puck 166.

The thermally conductive base 164 and/or electrostatic puck 166 mayinclude one or more optional embedded heating elements 176, embeddedthermal isolators 174 and/or conduits 168, 170 to control a lateraltemperature profile of the support assembly 148. The conduits 168, 170may be fluidly coupled to a fluid source 172 that circulates atemperature regulating fluid through the conduits 168, 170. The embeddedisolator 174 may be disposed between the conduits 168, 170 in oneembodiment. The heater 176 is regulated by a heater power source 178.The conduits 168, 170 and heater 176 may be utilized to control thetemperature of the thermally conductive base 164, thereby heating and/orcooling the electrostatic puck 166 and a substrate (e.g., a wafer) 144being processed. The temperature of the electrostatic puck 166 and thethermally conductive base 164 may be monitored using a plurality oftemperature sensors 190, 192, which may be monitored using a controller195.

The electrostatic puck 166 may further include multiple gas passagessuch as grooves, mesas and other surface features, that may be formed inan upper surface of the puck 166. The gas passages may be fluidlycoupled to a source of a heat transfer (or backside) gas such as He viaholes drilled in the puck 166. In operation, the backside gas may beprovided at controlled pressure into the gas passages to enhance theheat transfer between the electrostatic puck 166 and the substrate 144.

The electrostatic puck 166 includes at least one clamping electrode 180controlled by a chucking power source 182. The electrode 180 (or otherelectrode disposed in the puck 166 or base 164) may further be coupledto one or more RF power sources 184, 186 through a matching circuit 188for maintaining a plasma formed from process and/or other gases withinthe processing chamber 100. The sources 184, 186 are generally capableof producing RF signal having a frequency from about 50 kHz to about 3GHz and a power of up to about 10,000 Watts.

FIG. 2A depicts a deposition mechanism applicable to a variety ofdeposition techniques utilizing energetic particles such as ion assisteddeposition (IAD). Exemplary IAD methods include deposition processeswhich incorporate ion bombardment, such as evaporation (e.g., activatedreactive evaporation (ARE)) and sputtering in the presence of ionbombardment to form plasma resistant coatings as described herein. Oneparticular type of IAD performed in embodiments is electron beam IAD(EB-IAD). Any of the IAD methods may be performed in the presence of areactive gas species, such as O₂, N₂, halogens, etc. Such reactivespecies may burn off surface organic contaminants prior to and/or duringdeposition. Additionally, the IAD deposition process for ceramic targetdeposition vs. the metal target deposition can be controlled by partialpressure of O₂ ions in embodiments. For example a Y₂O₃ coating can bemade by evaporation of a Y metal and bleeding of oxygen ions to formoxides the Yttrium material on the surface of the component.Alternatively, a ceramic target can be used with no oxygen or reducedoxygen.

As shown, a thin film protective layer 215 is formed on an article 210or on multiple articles 210A, 210B by an accumulation of depositionmaterials 202 in the presence of energetic particles 203 such as ions.The deposition materials 202 may include atoms, ions, radicals, and soon. The energetic particles 203 may impinge and compact the thin filmprotective layer 215 as it is formed.

In one embodiment, EB IAD is utilized to form the thin film protectivelayer 215. FIG. 2B depicts a schematic of an IAD deposition apparatus.As shown, a material source 250 provides a flux of deposition materials202 while an energetic particle source 255 provides a flux of theenergetic particles 203, both of which impinge upon the article 210,210A, 210B throughout the IAD process. The energetic particle source 255may be an Oxygen or other ion source. The energetic particle source 255may also provide other types of energetic particles such as inertradicals, neutron atoms, and nano-sized particles which come fromparticle generation sources (e.g., from plasma, reactive gases or fromthe material source that provide the deposition materials).

The material source (e.g., a target body) 250 used to provide thedeposition materials 202 may be a bulk sintered ceramic corresponding tothe same ceramic that the thin film protective layer 215 is to becomposed of. For example, the material source may be a bulk sinteredceramic compound body, or bulk sintered YAG, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, orGd₃Al₅O₁₂, or other mentioned ceramics. Other target materials may alsobe used, such as powders, calcined powders, preformed material (e.g.,formed by green body pressing or hot pressing), or a machined body(e.g., fused material). All of the different types of material sources250 are melted into molten material sources during deposition. However,different types of starting material take different amounts of time tomelt. Fused materials and/or machined bodies may melt the quickest.Preformed material melts slower than fused materials, calcined powdersmelt slower than preformed materials, and standard powders melt moreslowly than calcined powders.

IAD may utilize one or more plasmas or beams (e.g., electron beams) toprovide the material and energetic ion sources. Reactive species mayalso be provided during deposition of the plasma resistant coating. Inone embodiment, the energetic particles 203 include at least one ofnon-reactive species (e.g., Ar) or reactive species (e.g., O). Infurther embodiments, reactive species such as CO and halogens (Cl, F,Br, etc.) may also be introduced during the formation of a plasmaresistant coating to further increase the tendency to selectively removedeposited material most weakly bonded to the thin film protective layer215.

With IAD processes, the energetic particles 203 may be controlled by theenergetic ion (or other particle) source 255 independently of otherdeposition parameters. According to the energy (e.g., velocity), densityand incident angle of the energetic ion flux, composition, structure,crystalline orientation and grain size of the thin film protective layermay be manipulated.

Additional parameters that may be adjusted are a temperature of thearticle during deposition as well as the duration of the deposition. Inone embodiment, an IAD deposition chamber (and the chamber lid or nozzletherein) is heated to a starting temperature of 160° C. or higher priorto deposition. In one embodiment, the starting temperature is 160° C. to500° C. In one embodiment, the starting temperature is 200° C. to 270°C. The temperature of the chamber and of the lid or nozzle may then bemaintained at the starting temperature during deposition. In oneembodiment, the IAD chamber includes heat lamps which perform theheating. In an alternative embodiment, the IAD chamber and lid or nozzleare not heated. If the chamber is not heated, it will naturally increasein temperature to about 160° C. as a result of the IAD process. A highertemperature during deposition may increase a density of the protectivelayer but may also increase a mechanical stress of the protective layer.Active cooling can be added to the chamber to maintain a low temperatureduring coating. The low temperature may be maintained at any temperatureat or below 160° C. down to 0° C. in one embodiment.

Additional parameters that may be adjusted are working distance 270 andangle of incidence 272. The working distance 270 is the distance betweenthe material source 250 and the article 210A, 210B. In one embodiment,the working distance is 0.2 to 2.0 meters, with a working distance of1.0 meters in one particular embodiment. Decreasing the working distanceincreases a deposition rate and increases an effectiveness of the ionenergy. However, decreasing the working distance below a particularpoint may reduce a uniformity of the protective layer. The angle ofincidence is an angle at which the deposition materials 202 strike thearticles 210A, 210B. In one embodiment the angle of incidence is 10-90degrees, with an angle of incidence of about 30 degrees in oneparticular embodiment.

IAD coatings can be applied over a wide range of surface conditions withroughness from about 0.5 micro-inches (μin) to about 180 μin. However,smoother surface facilitates uniform coating coverage. The coatingthickness can be up to about 300 microns (μm). In production, coatingthickness on components can be assessed by purposely adding a rare earthoxide based colored agent such Nd₂O₃, Sm₂O₃, Er₂O₃, etc. at the bottomof a coating layer stack. The thickness can also be accurately measuredusing ellipsometry.

IAD coatings can be amorphous or crystalline depending on the rare-earthoxide composite used to create the coating. For example EAG and YAG areamorphous coatings whereas Er₂O₃ and the ceramic compound comprisingY₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂ are typically crystalline.Amorphous coatings are more conformal and reduce lattice mismatchinduced epitaxial cracks whereas crystalline coatings are more erosionresistant.

Coating architecture can be a bi-layer or a multi-layer structure. In abilayer architecture, an amorphous layer can be deposited as a bufferlayer to minimize epitaxial cracks followed by a crystalline layer onthe top which might be erosion resistant. In a multi-layer design, layermaterials may be used to cause a smooth thermal gradient from thesubstrate to the top layer.

Co-deposition of multiple targets using multiple electron beam (e-beam)guns can be achieved to create thicker coatings as well as layeredarchitectures. For example, two targets having the same material typemay be used at the same time. Each target may be bombarded by adifferent electron beam gun. This may increase a deposition rate and athickness of the protective layer. In another example, two targets maybe different ceramic materials. A first electron beam gun may bombard afirst target to deposit a first protective layer, and a second electronbeam gun may subsequently bombard the second target to form a secondprotective layer having a different material composition than the firstprotective layer.

Post coating heat treatment can be used to achieve improved coatingproperties. For example, it can be used to convert an amorphous coatingto a crystalline coating with higher erosion resistance. Another exampleis to improve the coating to substrate bonding strength by formation ofa reaction zone or transition layer.

In one embodiment, multiple rings are processed in parallel in an IADchamber. For example, up to five rings may be processed in parallel inone embodiment. Each ring may be supported by a different fixture.Alternatively, a single fixture may be configured to hold multiplerings. The fixtures may move the supported rings during deposition.

In one embodiment, a fixture to hold a ring can be designed out of metalcomponents such as cold rolled steel or ceramics such as Al₂O₃, Y₂O₃,etc. The fixture may be used to support the ring above or below thematerial source and electron beam gun. The fixture can have a chuckingability to chuck the ring for safer and easier handling as well asduring coating. Also, the fixture can have a feature to orient or alignthe ring. In one embodiment, the fixture can be repositioned and/orrotated about one or more axes to change an orientation of the supportedring to the source material. The fixture may also be repositioned tochange a working distance and/or angle of incidence before and/or duringdeposition. The fixture can have cooling or heating channels to controlthe ring temperature during coating. The ability or reposition androtate the ring may enable maximum coating coverage of 3D surfaces ofthe rings since IAD is a line of sight process.

FIGS. 3-4 illustrate cross sectional side views of articles (e.g.,rings) covered by one or more thin film protective layers. A singlering, insert ring or other process kit ring for a plasma etch reactorused for conductor etch and dielectric etch processes is typically Si orSiO₂. However, Si and SiO₂ have high erosion rates when exposed tovarious etch chemistries. Other materials may also be used for therings.

Referring to FIG. 3, a body 305 of the article 300 includes a thin filmstack 306 having a first thin film protective layer 308 and a secondthin film protective layer 310. Alternatively, the article 300 mayinclude only a single thin film protective layer 308 on the body 305. Inone embodiment, the thin film protective layers 308, 310 have athickness of up to about 300 μm. In a further embodiment, the thin filmprotective layers have a thickness of below about 20 microns, and athickness between about 0.5 microns to about 7 microns in one particularembodiment. A total thickness of the thin film protective layer stack inone embodiment is 300 μm or less.

The thin film protective layers 308, 310 are deposited ceramic layersthat may be formed on the body 305 of the article 300 using an electronbeam ion assisted deposition (EB-IAD) process. The EB-IAD deposited thinfilm protective layers 308, 310 may have a relatively low film stress(e.g., as compared to a film stress caused by plasma spraying orsputtering). The relatively low film stress may cause the lower surfaceof the body 305 to be very flat, with a curvature of less than about 50microns over the entire body for a body with a 12 inch diameter. The IADdeposited thin film protective layers 308, 310 may additionally have aporosity that is less than 1%, and less than about 0.1% in someembodiments. Therefore, the IAD deposited protective layer is a densestructure, which can have performance benefits for application on ringsused in a plasma etch reactor. Additionally, the IAD depositedprotective layer may have a low crack density and a high adhesion to thebody 305. Additionally, the IAD deposited protective layers 308, 310 maybe deposited without first roughening the upper surface of the body 305or performing other time consuming surface preparation steps.

Examples of ceramics that may be used to form the thin film protectivelayer 208 include Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂,a ceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂(Y₂O₃—ZrO₂ solid solution), or any of the other ceramic materialspreviously identified. Other Er based and/or Gd based plasma resistantrare earth oxides may also be used to form the thin film protectivelayers 308, 310. In one embodiment, the same ceramic material is notused for two adjacent thin film protective layers. However, in anotherembodiment adjacent layers may be composed of the same ceramic.

Rings having IAD thin film protective layers may be used in applicationsthat apply a wide range of temperatures. For example, rings with IADthin film protective layers may be used in processes having temperaturesat 0° C. to temperatures at 1000° C. The rings may be used at hightemperatures (e.g., at or above 300° C.) without cracking caused bythermal shock.

TABLE 1 Material properties for IAD deposited YAG, Er₂O₃, EAG andceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.92% Ceramic Property Al₂O₃ Cmpd. YAG Er₂O₃ EAG Y₂O₃ YZ20 YF₃ Crystal C AA C A C C A Structure Breakdown 363  427  1223  527  900  1032 423  522 Voltage (V) (5 μm) (5 μm) (5 μm) Volume >0.01E16 4.1E16 11.3E16 — — — —— Resistivity (Ω · cm) Dielectric   9.2 9.83 +/− 0.04 9.76 +/− 0.01  9.67   9.54 — — — Constant Loss   5E−4   4E−4  4E−4   4E−4  4E−4 — — —Tangent Thermal 18   19.9   20.1  19.4  19.2 — — — Conductivity (W/m-K)Roughness 8-16 Same Same Same Same Same Same Same (μin) AdhesionN/A >28   >32   — — — — — Over 92% Al₂O₃ (MPa) Hermicity <1E−6 1.2E−94.4E−10 5.5E−9 9.5E−10 — 1.6E−7 2.6E−9 (leak rate) (cm³/s) Hardness  12.14    7.825   8.5    5.009    9.057 —   5.98    3.411 (GPa) WearRate   0.2    0.14    0.28    0.113    0.176 — — — (nm/RFhr)

Table 1 shows material properties for a substrate of 92% Al₂O₃ (alumina)and for various IAD thin film protective layers coating a substrate of92% Al₂O₃. In the table “C” represents a crystalline structure and “A”represents an amorphous structure. As shown, the alumina substrate has abreakdown voltage of 363 Volts/mil (V/mil). In contrast, a 5 micron (μm)coating of the IAD deposited ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂ has a breakdown voltage of 427 V (much morethan the normalized value of 363 Volts/mil for alumina). A 5 μm coatingof the IAD deposited YAG has a breakdown voltage of 1223 V. A 5 μmcoating of the IAD deposited Er₂O₃ has a breakdown voltage of 527 V. A 5μm coating of the IAD deposited EAG has a breakdown voltage of 900 V. A5 μm coating of the IAD deposited Y₂O₃ has a breakdown voltage of 1032V. A 5 μm coating of the IAD deposited YZ20 has a breakdown voltage of423 V. A 5 μm coating of the IAD deposited YF₃ has a breakdown voltageof 522V.

A volume resistivity of the alumina is around 0.01×10¹⁶ (0.01E16) Ω·cmat room temperature. A volume resistivity of the ceramic compound thinfilm protective layer is about 4.1E16 Ω·cm at room temperature, and avolume resistivity of the YAG thin film protective layer is about11.3E16 Ω·cm at room temperature.

A dielectric constant of the alumina is about 9.2, a dielectric constantof the ceramic compound thin film is about 9.83, a dielectric constantof the YAG thin film is about 9.76, a dielectric constant of the Er₂O₃thin film is about 9.67, and a dielectric constant of the EAG thin filmis about 9.54. A loss tangent of the alumina is about 5E-4, a losstangent of the ceramic compound thin film is about 4E-4, a loss tangentof the YAG thin film is about 4E-4, a loss tangent of the Er₂O₃ thinfilm is about 4E-4, and a loss tangent of the EAG thin film is about4E-4. A thermal conductivity of the alumina is about 18 W/m-K, a thermalconductivity of the ceramic compound thin film is about 19.9 W/m-K, athermal conductivity of the YAG thin film is about 20.1 W/m-K, a thermalconductivity of the Er₂O₃ thin film is about 19.4 W/m-K, and a thermalconductivity of the EAG thin film is about 19.2 W/m-K.

The alumina substrate may have a starting roughness of approximately8-16 micro-inches in one embodiment, and that starting roughness may beapproximately unchanged in all of the thin film protective layers. Theprotective layer may be polished to reduce a surface roughness (e.g., anaverage surface roughness) to 8 micro-inches or below after deposition.In one embodiment, the protective layer is polished to an averagesurface roughness of 5-6 micro-inches or below using a flame polish. Inone embodiment, the flame polish polishes the protective layer to anaverage surface roughness of 2-3 micro-inches.

Adhesion strength of the thin film protective layers to the aluminasubstrate may be above 28 mega pascals (MPa) for the ceramic compoundthin film and above 32 MPa for the YAG thin film. Adhesion strength maybe determined by measuring the amount of force used to separate the thinfilm protective layer from the substrate. Hermicity measures the sealingcapacity that can be achieved using the thin film protective layer. Asshown, a He leak rate of around 1E-6 cubic centimeters per second(cm³/s) can be achieved using alumina, a He leak rate of around 1.2E-9can be achieved using the ceramic compound, a He leak rate of around4.4E-10 can be achieved using YAG, a He leak rate of around 5.5E-9 canbe achieved using Er₂O₃, a He leak rate of around 2.6E-9 can be achievedusing YF3, a He leak rate of around 1.6E-7 can be achieved using YZ20,and a He leak rate of around 9.5E-10 can be achieved using EAG. Lower Heleak rates indicate an improved seal. Each of the example thin filmprotective layers has a lower He leak rate than typical Al₂O₃.

Each of Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, and theceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂have a high hardness that may resist wear during plasma processing. Asshown, alumina has a Vickers hardness (5 Kgf) of around 12.14 Gigapascals (GPa), the ceramic compound has a hardness of around 7.825 GPa,YAG has a hardness of around 8.5 GPa, Er₂O₃ has a hardness of around5.009 GPa, YZ20 has a hardness of around 5.98 GPa, YF₃ has a hardness ofaround 3.411 GPa and EAG has a hardness of around 9.057 GPa, A measuredwear rate of alumina is around 0.2 nanometers per radio frequency hour(nm/RFhr), a wear rate of the ceramic compound is about 0.14 nm/RFhr, awear rate of Er₂O₃ is about 0.113 nm/RFhr, and a wear rate of EAG isabout 0.176 nm/RFhr.

Note that the Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, andthe ceramic compound may be modified such that the material propertiesand characteristics identified above may vary by up to 30% in someembodiments. Accordingly, the described values for these materialproperties should be understood as example achievable values. Theceramic thin film protective layers described herein should not beinterpreted as being limited to the provided values.

FIG. 4 illustrates a cross sectional side view of another embodiment ofan article 400 having a thin film protective layer stack 406 depositedover a body 405 of the article 400. Article 400 is similar to article400, except that thin film protective layer stack 406 has four thin filmprotective layers 408, 410, 415, 418.

The thin film protective layer stacks (such as those illustrated) mayhave any number of thin film protective layers. The thin film protectivelayers in a stack may all have the same thickness, or they may havevarying thicknesses. Each of the thin film protective layers may have athickness of less than approximately 20 microns in some embodiments. Inone example, a first layer 408 may have a thickness of 6 microns, and asecond layer 410 may have a thickness of 6 microns. In another example,first layer 408 may be a YAG layer having a thickness of 3 microns,second layer 410 may be a compound ceramic layer having a thickness of 3microns, third layer 415 may be a YAG layer having a thickness of 3microns, and fourth layer 418 may be a compound ceramic layer having athickness of 3 microns.

The selection of the number of ceramic layers and the composition of theceramic layers to use may be based on a desired application and/or atype of article being coated. EAG and YAG thin film protective layersformed by IAD typically have an amorphous structure. In contrast, theIAD deposited compound ceramic and Er₂O₃ layers typically have acrystalline or nano-crystalline structure. Crystalline andnano-crystalline ceramic layers may generally be more erosion resistantthan amorphous ceramic layers. However, in some instances thin filmceramic layers having a crystalline structure or nano-crystallinestructure may experience occasional vertical cracks (cracks that runapproximately in the direction of the film thickness and approximatelyperpendicular to the coated surface). Such vertical cracks may be causedby lattice mismatch and may be points of attack for plasma chemistries.Each time the article is heated and cooled, the mismatch in coefficientsof thermal expansion between the thin film protective layer and thesubstrate that it coats can cause stress on the thin film protectivelayer. Such stress may be concentrated at the vertical cracks. This maycause the thin film protective layer to eventually peel away from thesubstrate that it coats. In contrast, if there are not vertical cracks,then the stress is approximately evenly distributed across the thinfilm. Accordingly, in one embodiment a first layer 408 in the thin filmprotective layer stack 406 is an amorphous ceramic such as YAG or EAG,and the second layer 410 in the thin film protective layer stack 406 isa crystalline or nano-crystalline ceramic such as the ceramic compoundor Er₂O₃. In such an embodiment, the second layer 410 may providegreater plasma resistance as compared to the first layer 408. By formingthe second layer 410 over the first layer 408 rather than directly overthe body 405, the first layer 408 acts as a buffer to minimize latticemismatch on the subsequent layer. Thus, a lifetime of the second layer410 may be increased.

In another example, each of the body, Y₃Al₅O₁₂ (YAG), Y₄Al₂O₉, Er₂O₃,Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, the ceramic compound comprising Y₄Al₂O₉ anda solid-solution of Y₂O₃—ZrO₂, and other ceramics may have a differentcoefficient of thermal expansion. The greater the mismatch in thecoefficient of thermal expansion between two adjacent materials, thegreater the likelihood that one of those materials will eventuallycrack, peel away, or otherwise lose its bond to the other material. Theprotective layer stacks 306, 406 may be formed in such a way to minimizemismatch of the coefficient of thermal expansion between adjacent layers(or between a layer and a body 305, 405). For example, body 405 may bealumina, and EAG may have a coefficient of thermal expansion that isclosest to that of alumina, followed by the coefficient of thermalexpansion for YAG, followed by the coefficient of thermal expansion forthe compound ceramic. Accordingly, first layer 408 may be EAG, secondlayer 410 may be YAG, and third layer 415 may be the compound ceramic inone embodiment.

In another example, the layers in the protective layer stack 406 may bealternating layers of two different ceramics. For example, first layer408 and third layer 415 may be YAG, and second layer 410 and fourthlayer 418 may be the compound ceramic. Such alternating layers mayprovide advantages similar to those set forth above in cases where onematerial used in the alternating layers is amorphous and the othermaterial used in the alternating layers is crystalline ornano-crystalline.

In some embodiments, one of more of the layers in the thin filmprotective layer stacks 306, 406 are transition layers formed using aheat treatment. If the body 305, 405 is a ceramic body, then a hightemperature heat treatment may be performed to promote interdiffusionbetween a thin film protective layer and the body. Additionally, theheat treatment may be performed to promote interdiffusion betweenadjacent thin film protective layers or between a thick protective layerand a thin film protective layer. Notably, the transition layer may be anon-porous layer. The transition layer may act as a diffusion bondbetween two ceramics, and may provide improved adhesion between theadjacent ceramics. This may help prevent a protective layer fromcracking, peeling off, or stripping off during plasma processing.

The thermal treatment may be a heat treatment at up to about 1400-1600degrees C. for a duration of up to about 24 hours (e.g., 3-6 hours inone embodiment). This may create an inter-diffusion layer between afirst thin film protective layer and one or more of an adjacent ceramicbody or second thin film protective layer. If the ceramic body is Al₂O₃,and the protective layer is composed of a compound ceramic Y₄Al₂O₉ (YAM)and a solid solution Y₂-xZr_(x)O₃ (Y₂O₃—ZrO₂ solid solution), then aY₃Al₅O₁₂ (YAG) interface layer will be formed. Similarly, a heattreatment will cause a transition layer of EAG to form between Er₂O₃ andAl₂O₃. A heat treatment will also cause a transition layer of YAG toform between Y₂O₃ and Al₂O₃. A heat treatment may also cause GAG to formbetween Gd₂O₃ and Al₂O₃. A heat treatment of yttria stabilized zirconia(YSZ) over Al₂O₃ can form a transition layer of the compound ceramic ofY₄Al₂O₉ (YAM) and a solid solution Y₂-xZr_(x)O₃. Other transition layersmay be formed between other adjacent ceramics.

In one embodiment, a coloring agent is added during the deposition ofthe first protective layer 308, 408. Accordingly, when the secondprotective layer 310, 410 wears away, an operator may have a visualqueue that it is time to refurbish or exchange the lid or nozzle.

FIG. 5 illustrates a perspective view of a single ring 505 having a thinfilm rare earth oxide plasma resistant layer 510, in accordance with oneembodiment. A zoomed in view 550 of the single ring 505 is also shown.The single ring 505 includes a ring inner side 552 and a ring outer side554. A plasma facing surface of the single ring 505 is coated by thethin film protective layer 510. The thin film protective layer 510 mayalso coat the ring outer side 554, which may also be exposed to plasmaduring processing. The protective layer 510 at a top flat region 515 ofthe ring 505 may be uniform, dense, and conforming, and may have nocracking and no delamination. The dense coating may have a porosity ofzero or close to zero (e.g., below 0.01%). In one embodiment, the thinfilm protective layer has a thickness of about 5 microns at the top flatregion 515. Alternatively, the thin film protective layer may bethicker.

The thin film protective layer 510 may coat one or more step 525 on thering inner side 552. The illustrated example shows a single step 525,but the ring inner side 552 may alternatively have two or more steps.The protective layer 510 at the step 525 of the ring 505 may be uniform,dense, and conforming, and may have no cracking and no delamination. Thedense coating may have a porosity of zero or close to zero (e.g., below0.01%). In one embodiment, the thin film protective layer 510 has athickness of about 5 microns at the step 525. Alternatively, the thinfilm protective layer may be thicker.

In some embodiments, the thin film protective layer 510 coats verticalwalls 520 of the ring inner side 552. Alternatively, the thin filmprotective layer 510 may not coat the vertical walls 520. The protectivelayer 510 at the vertical walls 520 of the ring 505 may be uniform,dense, and conforming, and may have no cracking and no delamination. Thedense coating may have a porosity of zero or close to zero (e.g., below0.01%). In one embodiment, the thin film protective layer 510 has athickness of about 3 microns at the vertical walls 520. Alternatively,the thin film protective layer at the vertical walls may be thicker. Inone embodiment a thickness of the thin film protective coating at thevertical walls is 45%-70% the thickness of the thin film protectivelayer at the top flat region 515 and at the step 525. In a furtherembodiment, the thickness of the thin film protective coating at thevertical walls is 55%-60% the thickness of the thin film protectivelayer at the top flat region 515 and at the step 525.

The single ring 505 may have a surface roughness of 16 micro-inches orhigher. However, the thin film protective layer 510 may be flamepolished to achieve a surface roughness of about 2-3 micro-inches in oneembodiment. The flame polish process may cause the protective layer tomelt and reflow at the surface to achieve the low surface roughness.

FIG. 6 illustrates one embodiment of a process 600 for forming a thinfilm protective layer over a body of a ring such as a single ring orinsert ring for a plasma etch reactor. At block 605 of process 600, aring is provided. The ring may have a bulk sintered ceramic body. Thebulk sintered ceramic body may be Al₂O₃, Y₂O₃, SiO₂, or the ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. The ringmay also be Si, SiC, or other materials.

At block 620, an ion assisted deposition (IAD) process is performed todeposit a rare earth oxide protective layer onto at least one surface ofthe ring. In one embodiment, an electron beam ion assisted depositionprocess (EB-IAD) is performed. The IAD process may be performed bymelting a material that is to be deposited and bombarding the materialwith ions.

The thin film protective layer may be Y₃Al₆O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃,Er₃Al₆O₁₂, Gd₃Al₆O₁₂, or the ceramic compound of Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, or other rare earth oxides describedherein. A deposition rate for the thin film protective layer may beabout 0.02-20 Angstroms per second (A/s) in one embodiment, and may bevaried by tuning deposition parameters. In one embodiment, a depositionrate of 0.25-1 A/s is initially used to achieve a conforming welladhering coating on the substrate. A deposition rate of 2-10 A/s maythen be used for depositing a remainder of a thin film protective layerto achieve a thicker coating in a shorter time. The thin film protectivelayers may be very conforming, may be uniform in thickness, and may havea good adhesion to the body/substrate that they are deposited on.

In one embodiment, the material includes a coloring agent that willcause the deposited protective layer to have a particular color.Examples of coloring agents that may be used include Nd₂O₃, Sm₂O₃ andEr₂O₃. Other coloring agents may also be used.

At block 625, a determination is made regarding whether to deposit anyadditional thin film protective layers. If an additional thin filmprotective layer is to be deposited, the process continues to block 630.At block 630, another thin film protective layer is formed over thefirst thin film protective layer. The other thin film protective layermay be composed of a ceramic that is different than a ceramic of thefirst thin film protective layer. Alternatively, the other thin filmprotective layer may be composed of the same ceramic or ceramics thatwere used to form the first protective layer.

In one embodiment, the other thin film protective layer does not includeany coloring agent. Accordingly, the subsequent protective layers mayhave a different color than the bottom protective layer, even if theyare composed of the almost the same ceramic materials. This causes thering to change color when the protective layer stack is eroded down tothe bottom protective layer. The change in color may signal to anoperator that it is time to change the ring of a processing chamber.

After a subsequent protective layer is deposited, the method returns toblock 625. If at block 625 no additional thin film protective layers areto be applied, the process proceeds to block 635. At block 635, asurface of the protective layer is polished using a flame polishprocess. In one embodiment, the surface of the top protective layer ispolished to a surface roughness of below 8 micro-inches. In anotherembodiment, the surface of the top protective layer is polished to asurface of about 2-3 micro-inches.

Process 600 may be performed on new rings or on used rings to refurbishthe used rings. In one embodiment, used rings are polished beforeperforming process 600. For example, previous protective layers may beremoved by polishing before performing process 600.

With IAD processes, the energetic particles may be controlled by theenergetic ion (or other particle) source independently of otherdeposition parameters. According to the energy (e.g., velocity), densityand incident angle of the energetic ion flux, composition, structure,crystalline orientation and grain size of the thin film protective layermay be manipulated. Additional parameters that may be adjusted are atemperature of the article during deposition as well as the duration ofthe deposition. The ion energy may be roughly categorized into lowenergy ion assist and high energy ion assist. Low energy ion assist mayinclude a voltage of about 230V and a current of about 5 A. High energyion assist may include a voltage of about 270V and a current of about 7A. The low and high energy for the ion assist is not limited to thevalues mentioned herein. The high and low level designation mayadditionally depend on the type of the ions used and/or the geometry ofthe chamber used to perform the IAD process. The ions are projected witha higher velocity with high energy ion assist than with low energy ionassist. Substrate (article) temperature during deposition may be roughlydivided into low temperature (around 120-150° C. in one embodiment whichis typical room temperature) and high temperature (around 270° C. in oneembodiment). For high temperature IAD deposition processes, the ring maybe heated prior to and during deposition.

TABLE 2A Example Thin Film Protective Layers Formed Using IAD Thk. Dep.Rate Ion Temp. Vacuum Hardness Material (μm) (A/s) Assist (° C. ) XRD(cm³/s) (GPa) 1^(st) Compound Ceramic 5 2 230V, 270 C N/A 4.11 (sinteredplug) 5A 2^(nd) Compound Ceramic 6 1 for 2 μm 230V, 270 C + A 5.0E−6(sintered plug) 2 for 4 μm 5A 3^(rd) Compound Ceramic 5 1 230V, 270 C +A 6.3E−6 (sintered plug) 5A 4^(th) Compound Ceramic 5 1 for 1 μm 270V,270 A 1.2E−9 7.825 (sintered plug) 2 for 4 μm 7A 5^(th) Compound Ceramic5 1 for 1 μm 270V,  120- A 1.2E−9 (calcined powder) 2 for 4 μm 7A 1506^(th) Compound Ceramic 5 1 for 1 μm 270V,  120- A 1.2E−9 7.812(calcined powder) 4 for 4 μm 7A 150

TABLE 2B Example Thin Film Protective Layers Formed Using IAD Thk. Dep.Rate Ion Temp. Vacuum Hardness Material (μm) (A/s) Assist (° C. ) XRD(cm³/s) (GPa) 1^(st) YAG 5 2.5 230V, 270 A 3.7E−7 5.7 (fused lump) 5A2^(nd) YAG 5 1 for 1 μm 270V, 270 A  4.4E−10 8.5 (fused lump) 2 for 4 μm7A Compound Ceramic/ 5 2   230V, 270 C +A 3.7E−7 YAG 5A 1^(st) Er₂O₃ 52   230V, 270 C   3E−6 (sintered lump) 5A 2^(nd) Er₂O₃ 5 1 for 1 μm270V, 270 C 5.5E−9 5.009 (sintered lump) 2 for 4 μm 7A 1^(st) EAG 7.5 1for 1 μm 270V, 270 A  9.5E−10 8.485 (calcined powder) 2 for next 7A2^(nd) EAG 7.5 1 for 1 μm 270V,  120- A 2.5E−9 9.057 (calcined power) 2for next 7A 150 3^(rd) EAG 5 1 for 1 μm 270V, A (calcined powder) 2 for4 μm 7A Y₂O₃ 5 1 for 1 μm 270V, 270 C (fused lump) 2 for 4 μm 7A YZ20 51 for 1 μm 270V,  120- C 1.6E−7 5.98 (Powder) 2 for 4 μm 7A 150 YF₃ 5 1for 1 μm 270V,  120- A 2.6E−9 3.411 2 for 4 μm 7A 150

Tables 2A-2B show multiple example thin film protective layers formedusing IAD with various deposition parameters. The experimental resultsidentify an optimized coating process based on a multi-factorial designof experiments (DOE) that varies ion assisted energy, deposition rateand temperature to obtain a conforming, dense microstructure. Thecoatings are characterized in terms of material properties(microstructure and/or crystal phase) and mechanical properties(hardness and adhesion), as well as crack density and vacuum sealingcapability. IAD coating process optimization can produce IAD coatingswith high density thin-films (up to ˜300 μm in thickness) with lowresidual stress. The optimized parameters can be used for most rareearth oxide based coating materials.

Six different examples are shown for thin film protective layers formedfrom the ceramic compound of Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.A first example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a low energy ionassist and a sintered plug target, a deposition temperature of 270° C.,and a deposition rate of 2 angstroms per seconds (A/s). X-raydiffraction showed that the first example compound ceramic thin filmprotective layer had a crystalline structure. The first example compoundceramic thin film protective layer also had a hardness of 4.11 GPa andvisual inspection showed good conformance to the underlying substrate aswell as some vertical cracks and some spikes.

A second example compound ceramic thin film protective layer has athickness of 6 microns, and was formed using IAD with a low energy ionassist and a sintered plug target, a deposition temperature of 270° C.,and a deposition rate of 1 A/s for the first 2 microns and a depositionrate of 2 A/s for the subsequent 4 microns. X-ray diffraction showedthat the second example compound ceramic thin film protective layer hada nano-crystalline structure (in which portions are crystalline andportions are amorphous). When used as a seal, the second examplecompound ceramic thin film protective layer was able to maintain avacuum down to 5E-6 cubic centimeters per second (cm³/s). Visualinspection of the second example compound ceramic thin film protectivelayer showed good conformance and fewer vertical cracks than the firstexample compound ceramic thin film protective layer.

A third example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a low energy ionassist and a sintered plug target, a deposition temperature of 270° C.,and a deposition rate of 1 A/s. X-ray diffraction showed that the thirdexample compound ceramic thin film protective layer had anano-crystalline structure. When used as a seal, the third examplecompound ceramic thin film protective layer was able to maintain avacuum down to 6.3E-6 cm³/s. Visual inspection of the third examplecompound ceramic thin film protective layer showed good conformance andfewer vertical cracks than the first example compound ceramic thin filmprotective layer.

A fourth example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a high energy ionassist and a sintered plug target, a deposition temperature of 270° C.,and a deposition rate of 1 A/s for the first micron and 2 A/s for thesubsequent 4 microns. X-ray diffraction showed that the third examplecompound ceramic thin film protective layer had an approximatelyamorphous structure. When used as a seal, the third example compoundceramic thin film protective layer was able to maintain a vacuum down to1.2E-9 cm³/s. Visual inspection of the fourth example compound ceramicthin film protective layer showed good conformance, a smooth surface andvery few vertical cracks. Additionally, the fourth example compoundceramic thin film protective layer has a hardness of 7.825 GPa.

A fifth example compound thin film protective layer was formed using thesame parameters as the fourth example compound thin film protectivelayer, but with a deposition temperature at room temperature (around120-150° C.) and with a calcined powder target. The fifth examplecompound thin film protective layer showed similar properties to thoseof the fourth example compound thin film protective layer.

A sixth example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a high energy ionassist and a calcined powder target, a deposition temperature of 270°C., and a deposition rate of 1 A/s for the first micron and 4 A/s forthe subsequent 4 microns. X-ray diffraction showed that the thirdexample compound ceramic thin film protective layer had an approximatelyamorphous structure. When used as a seal, the third example compoundceramic thin film protective layer was able to maintain a vacuum down to1.2E-9 cm³/s. The fourth example compound ceramic thin film protectivelayer has a hardness of 7.812 GPa.

A first example YAG thin film protective layer has a thickness of 5microns, and was formed using IAD with a low energy ion assist and afused lump target, a deposition temperature of 270° C., and a depositionrate of 2.5 A/s. X-ray diffraction showed that the first YAG ceramicthin film protective layer had an amorphous structure. The first YAGthin film protective layer also had a hardness of 5.7 GPa and visualinspection showed good conformance, minimal cracking and a smoothsurface.

A second example YAG thin film protective layer has a thickness of 5microns, and was formed using IAD with a high energy ion assist and afused lump target, a deposition temperature of 270° C., and a depositionrate of 1 A/s for a first micron and 2 A/s for the subsequent 4 microns.X-ray diffraction showed that the second YAG thin film protective layerhad an amorphous structure. The second YAG thin film protective layeralso had a hardness of 8.5 GPa and visual inspection showed goodconformance, reduced cracking compared to the first YAG thin film and asmooth surface.

An example thin film protective layer stack with alternating compoundceramic and YAG layers has a thickness of 5 microns, and was formedusing IAD with a low energy ion assist, a deposition temperature of 270°C., and a deposition rate of 2 A/s. X-ray diffraction showed that thealternating layers were amorphous (for the YAG layers) and crystallineor nano-crystalline (for the compound ceramic layers). Visual inspectionshowed reduced vertical cracks for the compound ceramic layers.

A first example Er₂O₃ thin film protective layer has a thickness of 5microns, and was formed using IAD with a low energy ion assist and asintered lump target, a deposition temperature of 270° C., and adeposition rate of 2 A/s. X-ray diffraction showed that the first Er₂O₃ceramic thin film protective layer had a crystalline structure. Visualinspection showed good conformance and a vertical cracking.

A second example Er₂O₃ thin film protective layer has a thickness of 5microns, and was formed using IAD with a high energy ion assist and asintered lump target, a deposition temperature of 270° C., and adeposition rate of 1 A/s for the first micron and a deposition rate of 2A/s for the subsequent 4 microns. X-ray diffraction showed that thesecond Er₂O₃ ceramic thin film protective layer had a crystallinestructure. Visual inspection showed good conformance and a less verticalcracking compared to the first Er₂O₃ ceramic thin film protective layer.

A first example EAG thin film protective layer has a thickness of 7.5microns, and was formed using IAD with a high energy ion assist and acalcined powder target, a deposition temperature of 270° C., and adeposition rate of 1 A/s for the first micron and a deposition rate of 2A/s for the subsequent microns. X-ray diffraction showed that the firstEAG ceramic thin film protective layer had an amorphous structure, andthe layer had a hardness of 8.485 GPa. Visual inspection showed goodconformance and minimal cracking.

A second example EAG thin film protective layer has a thickness of 7.5microns, and was formed using IAD with a high energy ion assist and acalcined powder target, a deposition temperature of 120-150° C., and adeposition rate of 1 A/s for the first micron and a deposition rate of 2A/s for the subsequent microns. X-ray diffraction showed that the secondEAG ceramic thin film protective layer had an amorphous structure, andthe layer had a hardness of 9.057 GPa. Visual inspection showed goodconformance and a less cracking compared to the first EAG ceramic thinfilm protective layer.

A third example EAG thin film protective layer has a thickness of 5microns, and was formed using IAD with a high energy ion assist and acalcined powder target, and a deposition rate of 1 A/s for the firstmicron and a deposition rate of 2 A/s for the subsequent microns. X-raydiffraction showed that the third EAG ceramic thin film protective layerhad an amorphous structure.

An example Y₂O₃ thin film protective layer has a thickness of 5 microns,and was formed using IAD with a high energy ion assist and a fused lumptarget, a temperature of 270° C., and a deposition rate of 1 A/s for thefirst micron and a deposition rate of 2 A/s for the subsequent microns.X-ray diffraction showed that the third EAG ceramic thin film protectivelayer had a crystalline structure.

An example YZ20 thin film protective layer has a thickness of 5 microns,and was formed using IAD with a high energy ion assist and a powdertarget, a temperature of 120-150° C., and a deposition rate of 1 A/s forthe first micron and a deposition rate of 2 A/s for the subsequentmicrons. X-ray diffraction showed that the YZ20 ceramic thin filmprotective layer had a crystalline structure. When used as a seal, theYZ20 ceramic thin film protective layer was able to maintain a vacuumdown to 1.6E-7 cm³/s. The YZ20 ceramic thin film protective layer had ahardness of 5.98 GPa

An example YF₃ thin film protective layer has a thickness of 5 microns,and was formed using IAD with a high energy ion assist, a temperature of120-150° C., and a deposition rate of 1 A/s for the first micron and adeposition rate of 2 A/s for the subsequent microns. X-ray diffractionshowed that the YF₃ ceramic thin film protective layer had an amorphousstructure. When used as a seal, the YF₃ ceramic thin film protectivelayer was able to maintain a vacuum down to 2.6E-9 cm³/s. The YF₃ceramic thin film protective layer had a hardness of 3.411 GPa

TABLE 3 Ring Optimized Coating Process Parameters Parameter AffectsOptimization Range Voltage (V) Density & 188 150-270 Conformance Current(A) Density & 7 5-7 Conformance Temperature (° C.) Film Stress, 150100-270 Crystalinity Deposition rate (A/s) Conformance 1 0.01-20  Angleof incidence Ability to coat 3D 30  0-90 (degrees) geometry Workingdistance (in.) Coating thickness, 50  10-300 deposition rate

Table 3 shows optimized IAD processing parameters for coating a ring, inaccordance with one embodiment. Table 3 additionally shows processingparameter ranges that may be used in some embodiments to deposit thinfilm protective layers. In one embodiment, an IAD process is performedusing a voltage of 150-270 Volts (V), a current of 5-7 Amps (A), atemperature of 100-270° C., a deposition rate of 0.01-20 Angstroms persecond (A/s), an angle of incidence of 0-90 degrees, and a workingdistance of 10-300 inches (in.). In another embodiment, an IAD processis performed using a voltage of 50-500V, a current of 1-50 A, atemperature of 20-500° C., a deposition rate of 0.01-20 A/s, a workingdistance of 10-300 inches, and an angle of incidence of 10-90 degrees.

The coating deposition rate can be controlled by adjusting an amount ofheat that is applied by an electron beam. The ion assist energy may beused to densify the coating and to accelerate the deposition of materialon the surface of the lid or nozzle. The ion assist energy can bemodified by adjusting the voltage and/or the current of the ion source.The current and voltage can be adjusted to achieve high and low coatingdensity, to manipulate the stress of the coating, and also to affect thecrystalinity of the coating. Ion assist energies in the range of 50-500V and 1-50 A may be used in some embodiments. Deposition rate may bevaried from 0.01 to 20 A/s.

In one embodiment, a high ion assist energy used with a ceramic compoundcomprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂ forms an amorphousprotective layer and a low ion assist energy used with the ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂ forms acrystalline protective layer. The ion assist energy can also be used tochange a stoichiometry of the protective layer. For example, a metallictarget can be used, and during deposition metallic material converts toa metal oxide by the incorporation of oxygen ions at the surface of thelid or nozzle. Also, using an oxygen gun the level of any metal oxidecoating can be changed and optimized to achieve desired coatingproperties. For example most rare earth oxides lose oxygen inside avacuum chamber. By bleeding more oxygen inside the chamber the oxygendeficiency of the oxide coating material can be compensated.

Coating temperature can be controlled by using heaters (e.g., heatlamps) and by controlling the deposition rate. A higher deposition ratewill typically cause the temperature of the lid or nozzle to increase.The deposition temperature can be varied to control a film stress,crystallinity, and so on. Temperature may be varied from 20° C. to 500°C.

The working distance can be adjusted to modify uniformity, density anddeposition rate. Working distance may be varied from 10-300 inches. Thedeposition angle or angle of incidence can be varied by the location ofthe electron beam gun or electron beam hearth, or by changing a locationof the lid or nozzle in relation to the electron beam gun or electronbeam hearth. By optimizing the deposition angle, a uniform coating inthree dimensional geometries can be achieved. Deposition angle can bevaried from 0-90 degrees, and from 10-90 degrees in one particularembodiment.

In one embodiment, an IAD process is performed using a voltage of about188 V in combination with other processing parameters having any of theassociated processing parameter ranges. In one embodiment, an IADprocess is performed using a current of about 7 A in combination withother processing parameters having any of the associated processingparameter ranges. In one embodiment, an IAD process is performed usingtemperature of about 150° C. in combination with other processingparameters having any of the associated processing parameter ranges. Inone embodiment, an IAD process is performed using a deposition rate ofabout 1 A/s in combination with other processing parameters having anyof the associated processing parameter ranges. In a further embodiment,a deposition rate of 2 A/s is used until a deposited thin film reaches athickness of 1 μm, after which a deposition rate of 1 A/s is used. Inanother embodiment, a deposition rate of 0.25-1 A/s is initially used toachieve a conforming well adhering coating on the substrate. Adeposition rate of 2-10 A/s may then be used for depositing a remainderof a thin film protective layer to achieve a thicker coating in ashorter time.

In one embodiment, an IAD process is performed using an angle ofincidence of about 30 degrees in combination with other processingparameters having any of the associated processing parameter ranges. Inone embodiment, an IAD process is performed using a working distance ofabout 50 inches in combination with other processing parameters havingany of the associated processing parameter ranges.

FIG. 7 shows erosion rates of various materials exposed to dielectricetch CF₄ chemistry, including erosion rates of multiple different IADcoatings generated in accordance with embodiments described herein. Asshown, an erosion rate of quartz is around 1.5.3 microns perradiofrequency hour (μm/Rfhr), an erosion rate of SiC is around 1.2μm/Rfhr, an erosion rate of Si—SiC is around 1.2 μm/Rfhr, an erosionrate of IAD deposited YAG is around 0.2 μm/Rfhr, an erosion rate of IADdeposited EAG is about 0.24 μm/Rfhr, an erosion rate of IAD depositedcompound ceramic is about 0.18 μm/Rfhr, an erosion rate of IAD depositedY₂O₃ is about 0.18 μm/Rfhr, and an erosion rate of IAD deposited Er2O3is about 0.18 μm/Rfhr. A radiofrequency hour is an hour of processing.

FIGS. 8-9 illustrate erosion rates for thin film protective layersformed in accordance with embodiments of the present invention. FIG. 8shows erosion rates of thin film protective layers when exposed to aCH₄/C1 ₂ plasma chemistry. As shown, the IAD deposited thin filmprotective layers show a much improved erosion resistance as compared toAl₂O₃. For example, alumina with a 92% purity showed an erosion rate ofaround 18 nanometers pre radiofrequency hour (nm/RFHr) and alumina witha 99.8% purity showed an erosion rate of about 56 nm/RFHr. In contrastan IAD deposited compound ceramic thin film protective layer showed anerosion rate of about 3 nm/RFHr and an IAD deposited YAG thin filmprotective layer showed an erosion rate of about 1 nm/RFHr.

FIG. 9 shows erosion rates of thin film protective layers when exposedto a H₂/NF₃ plasma chemistry. As shown, the IAD deposited thin filmprotective layers show a much improved erosion resistance as compared toAl₂O₃. For example, alumina with a 92% purity showed an erosion rate ofaround 190 nm/RFHr and alumina with a 99.8% purity showed an erosionrate of about 165 nm/RFHr. In contrast an IAD deposited YAG thin filmprotective layer showed an erosion rate of about 52 nm/RFHr. Similarly,a compound ceramic thin film protective layer deposited using IAD withlow energy ions showed an erosion rate of about 45 nm/RFHr and acompound ceramic thin film protective layer deposited using IAD withhigh energy ions showed an erosion rate of about 35 nm/RFHr. An EAG thinfilm protective layer deposited using IAD with high depositiontemperature (e.g., around 270° C.) showed an erosion rate of about 95nm/RFHr and an EAG thin film protective layer deposited using IAD withlow deposition temperature (e.g., around 120-150° C.) showed an erosionrate of about 70 nm/RFHr. An Er₂O₃ thin film protective layer depositedusing IAD with high energy ions showed an erosion rate of about 35nm/RFHr.

FIGS. 10-11 illustrate roughness profiles for thin film protectivelayers formed in accordance with embodiments of the present invention.FIG. 10 shows surface roughness profiles of thin film protective layersof FIG. 8 before and after exposure to a CH₄/C1 ₂ plasma chemistry for100 RFHrs. As shown, the IAD deposited thin film protective layers showa minimum change in surface roughness after exposure to a CH₄/C1 ₂plasma chemistry for 100 RFHrs.

FIG. 11 shows surface roughness profiles of thin film protective layersof FIG. 9 before and after exposure to an H₂/NF₃ plasma chemistry for 35RFHrs. As shown, the IAD deposited thin film protective layers show aminimum change in surface roughness after exposure to an H₂/NF₃ plasmachemistry for 35 RFHrs.

FIG. 12 shows erosion rates of various materials exposed to a CF₄—CHF₃trench chemistry at low bias, including erosion rates of multipledifferent IAD coatings generated in accordance with embodimentsdescribed herein. As shown, an erosion rate of 92% Alumina is around0.26 microns per radiofrequency hour (μm/Rfhr), an erosion rate of IADdeposited EAG is around 0.18 μm/Rfhr, an erosion rate of IAD depositedYAG is about 0.15 μm/Rfhr, an erosion rate of the plasma spray depositedcompound ceramic is about 0.09 μm/Rfhr, an erosion rate of IAD depositedY₂O₃ is about 0.08 μm/Rfhr, an erosion rate of IAD deposited ceramiccompound is about 0.07 μm/Rfhr, an erosion rate of bulk Y₂O₃ is about0.07 μm/Rfhr, an erosion rate of a bulk ceramic compound is about 0.065μm/Rfhr, and an erosion rate of IAD deposited Er₂O₃ is about 0.05μm/Rfhr. Similar etch results occur when these materials are etchedusing a CF₄—CHF₃ trench chemistry at a high bias. For example, at a highbias an etch rate of 92% Alumina is around 1.38 μm/Rfhr, an erosion rateof IAD deposited EAG is around 0.27 μm/Rfhr, an erosion rate of IADdeposited YAG is about 0.27 μm/Rfhr, an erosion rate of the plasma spraydeposited compound ceramic is about 0.35 μm/Rfhr, an erosion rate of IADdeposited Y₂O₃ is about 0.18 μm/Rfhr, an erosion rate of IAD depositedceramic compound is about 0.19 μm/Rfhr, an erosion rate of bulk Y₂O₃ isabout 0.4 μm/Rfhr, an erosion rate of a bulk ceramic compound is about0.4 μm/Rfhr, and an erosion rate of IAD deposited Er₂O₃ is about 0.18μm/Rfhr.

Particle analysis after a wet clean of rings coated with a thin filmrare earth oxide plasma resistant layer in accordance with embodimentsof the present invention has shown particle counts of 12,612 particlesper square centimeter (particles/cm²) for particles greater than orequal to 0.2 mm in size, as compared to a particle count of 47,400particles/cm² for particles greater than or equal to 0.2 mm in size withconventional rings. Particle counts of 3333 particles/cm² are shown forparticles greater than or equal to 0.3 mm in size, as compared to aparticle count of 12,720 particles/cm² for conventional rings. Particlecounts of 702 particles/cm² are shown for particles greater than orequal to 0.5 mm in size, as compared to a particle count of 3708particles/cm² for conventional rings. Particle counts of 108particles/cm² are shown for particles greater than or equal to 1.0 mm insize, as compared to a particle count of 1070 particles/cm² forconventional rings. Particle counts of 20 particles/cm² are shown forparticles greater than or equal to 2.0 mm in size, as compared to aparticle count of 320 particles/cm² for conventional rings. Accordingly,embodiments herein produce rings with particle counts that areapproximately 3.75 times lower than particle counts for traditionalrings. Additionally, the level or trace metal contamination for ringsproduced in accordance with embodiments herein is below or equal totrace metal contamination for conventional rings.

The preceding description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a good understanding of several embodiments of thepresent invention. It will be apparent to one skilled in the art,however, that at least some embodiments of the present invention may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present invention. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of the presentinvention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” When the term “about” or “approximately” is usedherein, this is intended to mean that the nominal value presented isprecise within ±30%.

Although the operations of the methods herein are shown and described ina particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be in an intermittentand/or alternating manner.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A chamber component for a processing chambercomprising: a ring shaped body comprising at least one of an oxide basedceramic, a nitride based ceramic or a carbide based ceramic, wherein thering shaped body is a sintered ceramic body comprising a top flatregion, a ring inner side and a ring outer side, wherein the ring innerside comprises an approximately vertical wall; and a protective layer onat least the top flat region, the ring inner side and the ring outerside of the ring shaped body, wherein the protective layer is aconformal layer comprising a plasma resistant rare earth oxide, has aporosity of less than 1%, has an average surface roughness of less than6 micro-inches, and has a first thickness of less than 300 μm on the topflat region and a second thickness on the approximately vertical wall ofthe ring inner side, wherein the second thickness is 45-70% of the firstthickness.
 2. The chamber component of claim 1, wherein the protectivelayer comprises at least one of Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃,Er₃Al₅O₁₂, Gd₃Al₅O₁₂, YF₃, Nd₂O₃, Er₄Al₂O₉, ErAlO₃, Gd₄Al₂O₉, GdAlO₃,Nd₃Al₅O₁₂, Nd₄Al₂O₉, NdAlO₃, or a ceramic compound comprising Y₄Al₂O₉and a solid-solution of Y₂O₃—ZrO₂.
 3. The chamber component of claim 1,wherein the protective layer has a thickness of 5-15 μm.
 4. The chambercomponent of claim 1, wherein the protective layer comprises a ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂, whereinthe ceramic compound has a composition consisting of 40-100 mol % ofY₂O₃, 0-60 mol % of ZrO₂, and 0-10 mol % of Al₂O₃.
 5. The chambercomponent of claim 1, wherein the protective layer comprises acombination of Y₂O₃, Zr₂O₃, Er₂O₃, Gd₂O₃ and SiO₂.
 6. The chambercomponent of claim 5, wherein the protective layer has a composition of40-45 mol % of Y₂O₃, 5-10 mol % of ZrO₂, 35-40 mol % of Er₂O₃, 5-10 mol% of Gd₂O₃, and 5-15 mol % of SiO₂.
 7. The chamber component of claim 1,wherein a porosity of the protective layer is below 0.1%.
 8. The chambercomponent of claim 1, where the protective layer comprises a protectivelayer stack comprising a first plasma resistant rare earth oxide film onthe at least one surface and a second plasma resistant rare earth oxidefilm on the first plasma resistant rare earth oxide film.
 9. The chambercomponent of claim 8, wherein the first plasma resistant rare earthoxide film comprises a coloring agent that causes the first plasmaresistant rare earth oxide film to have a different color than thesecond plasma resistant rare earth oxide film.
 10. The chamber componentof claim 9, wherein the coloring agent comprises at least one of Nd₂O₃,Sm₂O₃ or Er₂O₃.
 11. The chamber component of claim 9, wherein the firstplasma resistant rare earth oxide film is an amorphous layer comprisingY₃Al₅O₁₂ or Er₃Al₅O₁₂ and the second plasma resistant rare earth oxidefilm is a crystalline or polycrystalline layer comprising Er₂O₃ or aceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.12. The chamber component of claim 1, wherein the chamber component isusable at a temperature of 300° C. without causing cracking of theprotective layer.
 13. The chamber component of claim 1, furthercomprising: a transition layer between the ring shaped body and theprotective layer.
 14. The chamber component of claim 1, wherein theprotective layer comprises a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the ceramic compound has acomposition consisting of 40-60 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and30-40 mol % of Al₂O₃.
 15. The chamber component of claim 1, wherein theprotective layer comprises a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the ceramic compound has acomposition consisting of 40-60 mol % of Y₂O₃, 30-50 mol % of ZrO₂, and10-20 mol % of Al₂O₃.
 16. The chamber component of claim 1, wherein theprotective layer comprises a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the ceramic compound has acomposition consisting of 40-50 mol % of Y₂O₃, 20-40 mol % of ZrO₂, and20-40 mol % of Al₂O₃.
 17. The chamber component of claim 1, wherein theprotective layer comprises a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the ceramic compound has acomposition consisting of 70-90 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and10-20 mol % of Al₂O₃.
 18. The chamber component of claim 1, wherein theprotective layer comprises a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the ceramic compound has acomposition consisting of 60-80 mol % of Y₂O₃, 0-10 mol % of ZrO₂, and20-40 mol % of Al₂O₃.
 19. The chamber component of claim 1, wherein thering inner side further comprises a step and the ring outer side isrounded.
 20. A chamber component, comprising: a ring shaped bodycomprising at least one of an oxide based ceramic, a nitride basedceramic or a carbide based ceramic, wherein the ring shaped body is asintered ceramic body comprising a top flat region, a ring inner sideand a ring outer side, wherein the ring inner side comprises a step andan approximately vertical wall; and a protective layer on at least thetop flat region, the ring inner side and the ring outer side of the ringshaped body, wherein the protective layer is a conformal layer, has aporosity of less than 1%, has an average surface roughness of less than6 micro-inches, comprises at least one plasma resistant rare earth oxidefilm, and has a first thickness of less than 300 μm on the top flatregion and the step of the ring inner side and a second thickness on theapproximately vertical wall of the ring inner side, wherein the secondthickness is 45-70% of the first thickness.